WO2014091862A1 - Composite oxide material and exhaust gas purification catalyst using same - Google Patents

Composite oxide material and exhaust gas purification catalyst using same Download PDF

Info

Publication number
WO2014091862A1
WO2014091862A1 PCT/JP2013/080770 JP2013080770W WO2014091862A1 WO 2014091862 A1 WO2014091862 A1 WO 2014091862A1 JP 2013080770 W JP2013080770 W JP 2013080770W WO 2014091862 A1 WO2014091862 A1 WO 2014091862A1
Authority
WO
WIPO (PCT)
Prior art keywords
composite oxide
ceria
zirconia
pyrochlore
oxygen storage
Prior art date
Application number
PCT/JP2013/080770
Other languages
French (fr)
Japanese (ja)
Inventor
真秀 三浦
森川　彰
田辺　稔貴
Original Assignee
トヨタ自動車株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by トヨタ自動車株式会社 filed Critical トヨタ自動車株式会社
Priority to CN201380064838.0A priority Critical patent/CN104918891A/en
Priority to US14/439,940 priority patent/US20150290621A1/en
Priority to EP13862826.8A priority patent/EP2933231A4/en
Priority to RU2015122223A priority patent/RU2015122223A/en
Publication of WO2014091862A1 publication Critical patent/WO2014091862A1/en

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of rare earths
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/066—Zirconium or hafnium; Oxides or hydroxides thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/19—Catalysts containing parts with different compositions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/40—Catalysts, in general, characterised by their form or physical properties characterised by dimensions, e.g. grain size
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0236—Drying, e.g. preparing a suspension, adding a soluble salt and drying
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/03—Precipitation; Co-precipitation
    • B01J37/031—Precipitation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/12—Oxidising
    • B01J37/14—Oxidising with gases containing free oxygen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/16—Reducing
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G25/00—Compounds of zirconium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/206—Rare earth metals
    • B01D2255/2065—Cerium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/908—O2-storage component incorporated in the catalyst
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/30—Three-dimensional structures
    • C01P2002/36—Three-dimensional structures pyrochlore-type (A2B2O7)
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention relates to a composite oxide material having oxygen storage ability and an exhaust gas purification catalyst using the same.
  • Exhaust gas discharged from internal combustion engines such as automobiles contains harmful gases such as carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (HC).
  • CO carbon monoxide
  • NOx nitrogen oxides
  • HC unburned hydrocarbons
  • an exhaust gas purification catalyst silica-called three-way catalyst
  • a ceria-zirconia composite oxide having an oxygen storage capacity (OSC: Oxygen-Storage-Capacity) is used as a co-catalyst.
  • a substance having oxygen storage capacity oxygen storage material
  • a substance having oxygen storage capacity has an effect of controlling the air-fuel ratio (A / F) in a micro space by absorbing and releasing oxygen, and suppressing the reduction of the purification rate due to fluctuations in exhaust gas composition. . It is desirable that the oxygen storage material does not deteriorate even when exposed to high-temperature exhaust gas.
  • the content ratio of cerium and zirconium in the ceria-zirconia solid solution powder is set to a molar ratio of 43:57 to 48:52, and the ceria-zirconia solid solution powder is pressure-molded at a predetermined pressure.
  • the heat resistance of the obtained ceria-zirconia composite oxide is remarkably improved, and an extremely high level of excellent oxygen storage ability is exhibited even after being exposed to a high temperature for a long time. It is described that it becomes possible.
  • the ceria-zirconia composite oxide described in Patent Document 1 is said to be suitable for an exhaust gas purification catalyst used under relatively high temperature conditions of 300 ° C. or higher.
  • the ceria-zirconia composite oxide having a pyrochlore structure as described in Patent Document 1 is exposed to a temperature higher than expected, rearrangement occurs on the surface and the crystal structure becomes unstable. As a result, the oxygen storage capacity is expected to decrease. Therefore, there is a demand for an oxygen storage material that is superior in stability at high temperatures.
  • the present inventors have rearranged the ceria-zirconia composite oxide having a pyrochlore structure into a fluorite structure at a high temperature, and even if the ceria-zirconia composite oxide having a fluorite structure has a zirconia content.
  • the content is higher than the ceria content (zirconia rich)
  • the surface of the ceria-zirconia composite oxide crystal particle having a pyrochlore structure has a fluorite structure and is rich in zirconia.
  • the present inventors have conceived that the stability of a ceria-zirconia composite oxide having a pyrochlore structure can be improved by modifying or coating with a crystal of a certain ceria-zirconia composite oxide.
  • the gist of the present invention is as follows.
  • crystal grains having a pyrochlore structure of ceria-zirconia composite oxide, and crystals having a fluorite structure of ceria-zirconia composite oxide present on the particle surface The crystal having a fluorite structure of the ceria-zirconia composite oxide is characterized in that it contains more zirconia than ceria and is integrated with crystal grains having the pyrochlore structure of the ceria-zirconia composite oxide.
  • Composite oxide material is characterized in that it contains more zirconia than ceria and is integrated with crystal grains having the pyrochlore structure of the ceria-zirconia composite oxide.
  • An oxygen storage material for exhaust gas purification catalyst comprising the composite oxide material according to (1) or (2).
  • An exhaust gas purification catalyst comprising the composite oxide material according to (1) or (2).
  • the composite oxide material of the present invention has a high oxygen storage capacity and has a characteristic that the oxygen storage capacity is hardly lowered even at high temperatures.
  • the composite oxide material of the present invention is particularly useful as an oxygen storage material for exhaust gas purification catalysts.
  • the composite oxide material of the present invention comprises particles of ceria-zirconia composite oxide having a pyrochlore structure (Ce 2 Zr 2 O 7 : hereinafter also referred to as pyrochlore-type ceria-zirconia composite oxide or pyrochlore CZ), that is, primary And a crystal of a ceria-zirconia composite oxide having a fluorite structure and being rich in zirconia ((Zr 1-x , Ce x ) O 2 , where x ⁇ 0.5: hereinafter also referred to as zirconia-rich fluorite-type ceria-zirconia composite oxide or zirconia-rich fluorite-type CZ).
  • a pyrochlore structure Ce 2 Zr 2 O 7 : hereinafter also referred to as pyrochlore-type ceria-zirconia composite oxide or pyrochlore CZ
  • a crystalline phase (pyrochlore phase) having a pyrochlore-type ordered arrangement structure of cerium ions and zirconium ions is formed.
  • the pyrochlore CZ has an oxygen defect site, and an oxygen atom enters the site, whereby the pyrochlore phase changes to a ⁇ phase (Ce 2 Zr 2 O 8 ).
  • the ⁇ phase can change into a pyrochlore phase by releasing oxygen atoms.
  • the oxygen storage capacity of the ceria-zirconia composite oxide having a pyrochlore structure is due to the absorption and release of oxygen by a phase change between the pyrochlore phase and the ⁇ phase.
  • the pyrochlore CZ When the pyrochlore CZ is used as an oxygen storage material for the exhaust gas catalyst, the pyrochlore CZ changes to a pyrochlore phase when rich and changes to a ⁇ phase when lean.
  • the ⁇ phase of the ceria-zirconia composite oxide changes into a crystal phase having a fluorite structure (CeZrO 4 : fluorite type phase) by rearrangement. Therefore, when lean, particularly when the temperature is lean, the pyrochlore CZ is likely to undergo a phase change through the ⁇ phase to a fluorite phase inferior to the pyrochlore CZ in oxygen storage capacity.
  • Such a phase change is thought to arise from the surface of the pyrochlore CZ particles (surface rearrangement). Due to the surface rearrangement of the pyrochlore CZ particles, the oxygen storage capacity of the pyrochlore CZ is lowered.
  • the composite oxide material of the present invention having the structure as described above has a surface rearrangement caused by applying heat to the pyrochlore CZ particles prepared by a conventionally known method, and the fluorite phase generated on the surface. It can be obtained by doping zirconia into the zirconia.
  • a specific preparation method for example, an aqueous solution in which pyrochlore CZ particles and zirconium salt (zirconium oxynitrate, etc.) are dissolved is evaporated to dryness, or a zirconium salt is dissolved in an aqueous solution in which pyrochlore CZ particles are suspended.
  • the powder obtained by adding an aqueous solution and neutralizing with an aqueous ammonia solution or the like is calcined in the atmosphere.
  • this preparation method it is considered that the surface rearrangement of the pyrochlore CZ particles and the zirconia dope occur simultaneously in the firing process.
  • the pyrochlore CZ particles and the zirconia-rich fluorite-type CZ formed on the surface thereof are integrated, that is, fused and stabilized, and have no obvious interface. A structure that cannot be easily separated can be used.
  • the doping amount of zirconium is preferably 1 to 20% by weight in terms of zirconia with respect to the weight of the pyrochlore CZ particles.
  • the ratio of the content of cerium and zirconium is in the range of 53.5: 46.5 to 45:55 by weight. Preferably there is.
  • the composite oxide material of the present invention since the surface of the pyrochlore CZ particles is modified or coated with zirconia-rich fluorite-type CZ, the decrease in oxygen storage capacity due to the surface rearrangement of the pyrochlore CZ particles is suppressed. Furthermore, since the zirconia-rich fluorite-type CZ itself also has a relatively high oxygen storage capacity, the high oxide storage capacity is maintained in the composite oxide material of the present invention that is used for modification or coating of pyrochlore CZ particles.
  • the surface has a higher oxygen storage capacity than pyrochlore CZ particles that are not modified or coated so that the surface tends to have a fluorite structure. Therefore, the composite oxide material of the present invention has a high oxygen storage capacity and has a characteristic that the oxygen storage capacity is not easily lowered even at a high temperature.
  • the composite oxide material of the present invention is particularly suitable as an oxygen storage material for an exhaust gas purification catalyst.
  • Sample preparation 121.8 g of cerium nitrate hexahydrate, 88.0 g of zirconium oxynitrate dihydrate, and 34.6 g of 18% hydrogen peroxide solution were dissolved in 500 mL of ion-exchanged water. Using this solution and a 25% aqueous ammonia solution (300 g), a hydroxide precipitate was obtained by the reverse coprecipitation method. The obtained precipitate was separated by filtration, heated in a drying furnace at 150 ° C. for 7 hours to remove moisture, and then baked in an electric furnace at 400 ° C. for 5 hours. The obtained powder was pulverized using a ball mill to obtain a ceria-zirconia solid solution powder (1 ⁇ m-CZ powder) having an average particle diameter of 1 ⁇ m.
  • a pressure molding machine (WET CIP device) a pressure of 3000 kgf / cm 2 was applied to form a 1 ⁇ m-CZ powder, which was then heated in a graphite crucible containing activated carbon at 1700 ° C. for 5 hours in an Ar atmosphere. Reduced. The product was oxidized by calcination at 500 ° C. for 5 hours in the air in an electric furnace to obtain a pyrochlore-type ceria-zirconia composite oxide (pyrochlore CZ). Pyrochlore CZ was pulverized to an average secondary particle size of 11 ⁇ m using a ball mill.
  • An 11 ⁇ m-pyrochlor CZ powder was prepared by the same procedure as in the comparative example.
  • 11 ⁇ m-pyrochlor CZ powder 10.0 g and zirconium oxynitrate dihydrate (2.25 g) were dissolved in 50 mL of ion-exchanged water and evaporated to dryness with stirring.
  • the product was then heated in a drying furnace at 150 ° C. for 7 hours to remove moisture, and then baked in an electric furnace at 500 ° C. for 2 hours.
  • the obtained powder was further baked in an electric furnace at 900 ° C. for 3 hours in the air to obtain a zirconia-rich fluorite-type CZ-modified pyrochlore CZ of the present invention.
  • FIG. 1 is a diagram showing the results of STEM-EDX line analysis. The left side shows the spectrum obtained by conducting the elemental analysis along the line shown in the TEM image and the right side in the TEM image.
  • the Ce / Zr composition change in the vicinity of the surface is not recognized.
  • the zirconia-rich fluorite-type CZ-modified pyrochlore CZ of the present invention the Zr concentration is higher than the Ce concentration near the surface, and it can be seen that the clear structure is different from the pyrochlore CZ of the comparative example.
  • FIG. 2 is a diagram showing the IFFT analysis results of the samples obtained in the examples.
  • a TEM image and an inverse Fourier transform image (IFFT image) of a spot characteristic of pyrochlore seen in an FFT figure are shown. From the IFFT image, it is understood that in the sample of this example, the long-period structure collapses in the region near the surface having a width of about 30 nm shown in FIG. 2 and has a fluorite structure.
  • IFFT image inverse Fourier transform image
  • High temperature durability test The samples obtained in the above comparative examples and examples were subjected to a high temperature durability test. However, in order to align the thermal history of the sample, the sample of the comparative example was fired at 900 ° C. for 3 hours in the atmosphere in an electric furnace in advance before being subjected to the test. The high temperature endurance test was performed by heating the sample in an electric furnace at 1100 ° C. for 5 hours in an air atmosphere and measuring the oxygen storage capacity (OSC) after the treatment.
  • OSC oxygen storage capacity
  • the sample after the initial or endurance test was physically mixed with 0.25 wt% -Pd / Al 2 O 3 powder at a weight ratio of 1: 1.
  • the obtained powder was molded by applying a pressure of 1000 kgf / cm 2 using a pressure molding machine (WET CIP apparatus), and pulverized and sieved to produce 1 mm square pellets. 3.0 g of pellets were placed in a fixed bed circulation device, and an evaluation gas with a total flow rate of 15 L was used.
  • the temperature of the evaluation gas was 400 ° C., 500 ° C. or 600 ° C.
  • the amount of O 2 released from the sample was calculated from the CO 2 generation amount (2 minutes) during the flow of 1% -O 2 (N 2 balance) based on the reaction equation of CO + 1/2 O 2 ⁇ CO 2 . Since the release of oxygen from cerium is represented by the reaction formula 2CeO 2 ⁇ Ce 2 O 3 +1/2 O 2 , the theoretical limit value of lattice oxygen in the material determined from the amount of charged Ce and the released O Based on the two quantities, the CeO 2 utilization rate was determined.
  • FIG. 3 shows the results of tests conducted on the pyrochlore CZ of the comparative example and the surface zirconium-modified pyrochlore CZ of the example.
  • the utilization rate of CeO 2 in the pyrochlore CZ of the comparative example has decreased after the durability test, whereas the durability of the surface zirconia-modified pyrochlore CZ of the example has decreased.
  • the utilization rate of CeO 2 was higher than the initial performance of the pyrochlore CZ of the comparative example.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Biomedical Technology (AREA)
  • Combustion & Propulsion (AREA)
  • Health & Medical Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Catalysts (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Abstract

The purpose of the invention is to provide an oxygen storage material for an exhaust gas purification catalyst having better stability at high temperatures. The invention provides a composite oxide material characterized by containing: crystal grains having a pyrochlore structure of ceria-zirconia composite oxide; and crystals having a fluorite structure of ceria-zirconia composite oxide present on the surface of the above-mentioned grains; the crystals having a fluorite structure of ceria-zirconia composite oxide containing more zirconia than ceria and being integrated with the crystal grains having a pyrochlore structure of ceria-zirconia composite oxide. This composite oxide material has high oxygen storage capacity and characteristically resists a decline in oxygen storage capacity even at high temperatures.

Description

複合酸化物材料およびそれを用いた排ガス浄化触媒Composite oxide material and exhaust gas purification catalyst using the same
　本発明は、酸素貯蔵能を有する複合酸化物材料およびそれを用いた排ガス浄化触媒に関する。 The present invention relates to a composite oxide material having oxygen storage ability and an exhaust gas purification catalyst using the same.
　自動車などの内燃機関から排出される排ガスには、一酸化炭素（ＣＯ）、窒素酸化物（ＮＯｘ）、未燃の炭化水素（ＨＣ）などの有害ガスが含まれている。そのような有害ガスを分解する排ガス浄化触媒（いわゆる三元触媒）には、助触媒として酸素貯蔵能（ＯＳＣ：Oxygen Storage Capacity）を有するセリア－ジルコニア複合酸化物などが用いられる。酸素貯蔵能を有する物質（酸素貯蔵材）は、酸素を吸放出することによりミクロな空間で空燃比（Ａ／Ｆ）を制御し、排ガス組成変動に伴う浄化率の低下を抑制する効果を奏する。酸素貯蔵材は高温の排気ガスに晒されても劣化しないことが望まれる。 Exhaust gas discharged from internal combustion engines such as automobiles contains harmful gases such as carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (HC). As such an exhaust gas purification catalyst (so-called three-way catalyst) for decomposing harmful gases, a ceria-zirconia composite oxide having an oxygen storage capacity (OSC: Oxygen-Storage-Capacity) is used as a co-catalyst. A substance having oxygen storage capacity (oxygen storage material) has an effect of controlling the air-fuel ratio (A / F) in a micro space by absorbing and releasing oxygen, and suppressing the reduction of the purification rate due to fluctuations in exhaust gas composition. . It is desirable that the oxygen storage material does not deteriorate even when exposed to high-temperature exhaust gas.
　特許文献１には、セリア－ジルコニア固溶体粉末におけるセリウムとジルコニウムとの含有比率をモル比で４３：５７～４８：５２の範囲とし、そのセリア－ジルコニア固溶体粉末を所定の圧力で加圧成型した後に所定の温度条件で還元処理することにより、得られるセリア－ジルコニア複合酸化物の耐熱性が顕著に向上し、長時間高温に晒された後においても極めて高水準の優れた酸素貯蔵能を発揮させることが可能となることが記載されている。 In Patent Document 1, the content ratio of cerium and zirconium in the ceria-zirconia solid solution powder is set to a molar ratio of 43:57 to 48:52, and the ceria-zirconia solid solution powder is pressure-molded at a predetermined pressure. By performing the reduction treatment under a predetermined temperature condition, the heat resistance of the obtained ceria-zirconia composite oxide is remarkably improved, and an extremely high level of excellent oxygen storage ability is exhibited even after being exposed to a high temperature for a long time. It is described that it becomes possible.
特開２０１１－２１９３２９号JP2011-219329A
　特許文献１に記載のセリア－ジルコニア複合酸化物は、３００℃以上の比較的高温の条件下において用いる排ガス浄化用触媒に適しているとされている。しかし、特許文献１に記載されているようなパイロクロア構造を有するセリア－ジルコニア複合酸化物は、想定を越えた高温に晒された場合、表面において再配列がおこり結晶構造が不安定になることに起因して酸素貯蔵能が低下することが予想される。そのため、高温下における安定性により優れた酸素貯蔵材が求められている。 The ceria-zirconia composite oxide described in Patent Document 1 is said to be suitable for an exhaust gas purification catalyst used under relatively high temperature conditions of 300 ° C. or higher. However, when the ceria-zirconia composite oxide having a pyrochlore structure as described in Patent Document 1 is exposed to a temperature higher than expected, rearrangement occurs on the surface and the crystal structure becomes unstable. As a result, the oxygen storage capacity is expected to decrease. Therefore, there is a demand for an oxygen storage material that is superior in stability at high temperatures.
　本発明者らは、パイロクロア構造を有するセリア－ジルコニア複合酸化物が高温下において蛍石構造へと再配列すること、および蛍石構造を有するセリア－ジルコニア複合酸化物であってもジルコニア含有量がセリア含有量よりも多い場合（ジルコニアリッチ）には酸素吸放出速度が速いことに着目し、パイロクロア構造を有するセリア－ジルコニア複合酸化物の結晶粒子の表面を、蛍石構造を有しジルコニアリッチであるセリア－ジルコニア複合酸化物の結晶で修飾あるいは被覆した構成とすることにより、パイロクロア構造を有するセリア－ジルコニア複合酸化物の安定性を高めることに想到した。本発明の要旨は以下のとおりである。 The present inventors have rearranged the ceria-zirconia composite oxide having a pyrochlore structure into a fluorite structure at a high temperature, and even if the ceria-zirconia composite oxide having a fluorite structure has a zirconia content. When the content is higher than the ceria content (zirconia rich), paying attention to the high oxygen absorption / release rate, the surface of the ceria-zirconia composite oxide crystal particle having a pyrochlore structure has a fluorite structure and is rich in zirconia. The present inventors have conceived that the stability of a ceria-zirconia composite oxide having a pyrochlore structure can be improved by modifying or coating with a crystal of a certain ceria-zirconia composite oxide. The gist of the present invention is as follows.
（１）セリア－ジルコニア複合酸化物のパイロクロア構造を有する結晶粒子と、前記粒子表面に存在するセリア－ジルコニア複合酸化物の蛍石構造を有する結晶とを含み、
　前記セリア－ジルコニア複合酸化物の蛍石構造を有する結晶が、セリアよりもジルコニアを多く含み、かつ前記セリア－ジルコニア複合酸化物のパイロクロア構造を有する結晶粒子と一体化されていることを特徴とする複合酸化物材料。 (1) crystal grains having a pyrochlore structure of ceria-zirconia composite oxide, and crystals having a fluorite structure of ceria-zirconia composite oxide present on the particle surface,
The crystal having a fluorite structure of the ceria-zirconia composite oxide is characterized in that it contains more zirconia than ceria and is integrated with crystal grains having the pyrochlore structure of the ceria-zirconia composite oxide. Composite oxide material.
（２）セリア－ジルコニア複合酸化物のパイロクロア構造を有する結晶粒子に、ジルコニア換算で前記結晶粒子の１～２０重量％のジルコニウムをドープして前記蛍石構造を有する結晶を形成させることにより得られる、（１）に記載の複合酸化物材料。 (2) It is obtained by doping a crystal particle having a pyrochlore structure of a ceria-zirconia composite oxide with 1 to 20% by weight of zirconium in terms of zirconia to form a crystal having the fluorite structure. The composite oxide material according to (1).
（３）（１）または（２）に記載の複合酸化物材料からなる排ガス浄化触媒用酸素貯蔵材。 (3) An oxygen storage material for exhaust gas purification catalyst, comprising the composite oxide material according to (1) or (2).
（４）（１）または（２）に記載の複合酸化物材料を含む排ガス浄化触媒。 (4) An exhaust gas purification catalyst comprising the composite oxide material according to (1) or (2).
　本発明の複合酸化物材料は、高い酸素貯蔵能を有し、かつ高温下においても酸素貯蔵能が低下しにくい特性を有する。本発明の複合酸化物材料は、排ガス浄化触媒用酸素貯蔵材として特に有用である。 The composite oxide material of the present invention has a high oxygen storage capacity and has a characteristic that the oxygen storage capacity is hardly lowered even at high temperatures. The composite oxide material of the present invention is particularly useful as an oxygen storage material for exhaust gas purification catalysts.
　本明細書は、本願の優先権の基礎である特願２０１２－２７１３８７号の明細書、特許請求の範囲および図面に記載された内容を包含する。 This specification includes the contents described in the specification, claims and drawings of Japanese Patent Application No. 2012-271387, which is the basis of the priority of the present application.
比較例および実施例で得たサンプルのＳＴＥＭ－ＥＤＸライン分析の結果を表す図である。It is a figure showing the result of the STEM-EDX line analysis of the sample obtained by the comparative example and the Example. 実施例で得たサンプルのＩＦＦＴ解析結果を示す図である。It is a figure which shows the IFFT analysis result of the sample obtained in the Example. 比較例のパイロクロアＣＺと実施例の表面ジルコニウム修飾パイロクロアＣＺとについて試験を行った結果を示す図である。It is a figure which shows the result of having tested about the pyrochlore CZ of a comparative example, and the surface zirconium modification pyrochlore CZ of an Example.
　本発明の複合酸化物材料は、パイロクロア構造を有するセリア－ジルコニア複合酸化物の結晶（Ｃｅ２Ｚｒ２Ｏ７：以下、パイロクロア型セリア－ジルコニア複合酸化物あるいはパイロクロアＣＺとも称する）の粒子、すなわち一次粒子または二次粒子と、少なくとも一部においてその結晶粒子の表面を修飾あるいは被覆するように存在する、蛍石構造を有しジルコニアリッチであるセリア－ジルコニア複合酸化物の結晶（（Ｚｒ１－ｘ，Ｃｅｘ）Ｏ２、ただし式中ｘ＜０．５である：以下、ジルコニアリッチ蛍石型セリア－ジルコニア複合酸化物あるいはジルコニアリッチ蛍石型ＣＺとも称する）を含むことを特徴とする。 The composite oxide material of the present invention comprises particles of ceria-zirconia composite oxide having a pyrochlore structure (Ce 2 Zr 2 O 7 : hereinafter also referred to as pyrochlore-type ceria-zirconia composite oxide or pyrochlore CZ), that is, primary And a crystal of a ceria-zirconia composite oxide having a fluorite structure and being rich in zirconia ((Zr 1-x , Ce x ) O 2 , where x <0.5: hereinafter also referred to as zirconia-rich fluorite-type ceria-zirconia composite oxide or zirconia-rich fluorite-type CZ).
　セリア－ジルコニア複合酸化物において、パイロクロア構造を有するとは、セリウムイオンとジルコニウムイオンとによるパイロクロア型の規則配列構造を有する結晶相（パイロクロア相）が構成されていることを意味する。パイロクロアＣＺは酸素欠陥サイトを有し、そのサイトに酸素原子が入り込むことでパイロクロア相はκ相（Ｃｅ２Ｚｒ２Ｏ８）に相変化する。一方、κ相は酸素原子を放出することによりパイロクロア相に相変化することができる。パイロクロア構造を有するセリア－ジルコニア複合酸化物の酸素貯蔵能は、パイロクロア相とκ相との間で相互に相変化して酸素を吸放出することによるものである。 In the ceria-zirconia composite oxide, having a pyrochlore structure means that a crystalline phase (pyrochlore phase) having a pyrochlore-type ordered arrangement structure of cerium ions and zirconium ions is formed. The pyrochlore CZ has an oxygen defect site, and an oxygen atom enters the site, whereby the pyrochlore phase changes to a κ phase (Ce 2 Zr 2 O 8 ). On the other hand, the κ phase can change into a pyrochlore phase by releasing oxygen atoms. The oxygen storage capacity of the ceria-zirconia composite oxide having a pyrochlore structure is due to the absorption and release of oxygen by a phase change between the pyrochlore phase and the κ phase.
　パイロクロアＣＺを排ガス触媒の酸素貯蔵材として用いる場合、リッチ時にはパイロクロア相に変化し、リーン時にはκ相に変化することになる。ここで、セリア－ジルコニア複合酸化物のκ相は、再配列により蛍石構造を有する結晶相（ＣｅＺｒＯ４：蛍石型相）に相変化することが知られている。従って、リーン時、特に高温リーン時には、パイロクロアＣＺはκ相を経て酸素貯蔵能においてパイロクロアＣＺよりも劣る蛍石型相に相変化しやすくなる。そのような相変化はパイロクロアＣＺ粒子の表面から生じると考えられる（表面再配列）。パイロクロアＣＺ粒子の表面再配列により、パイロクロアＣＺの酸素貯蔵能は低下してしまう。 When the pyrochlore CZ is used as an oxygen storage material for the exhaust gas catalyst, the pyrochlore CZ changes to a pyrochlore phase when rich and changes to a κ phase when lean. Here, it is known that the κ phase of the ceria-zirconia composite oxide changes into a crystal phase having a fluorite structure (CeZrO 4 : fluorite type phase) by rearrangement. Therefore, when lean, particularly when the temperature is lean, the pyrochlore CZ is likely to undergo a phase change through the κ phase to a fluorite phase inferior to the pyrochlore CZ in oxygen storage capacity. Such a phase change is thought to arise from the surface of the pyrochlore CZ particles (surface rearrangement). Due to the surface rearrangement of the pyrochlore CZ particles, the oxygen storage capacity of the pyrochlore CZ is lowered.
　しかしながら、蛍石構造を有するセリア－ジルコニア複合酸化物であっても、組成の変化により酸素吸放出速度が変化し、ジルコニア含有量がセリア含有量よりも多い場合には酸素吸放出速度が速いことが知られている。セリア（ＣｅＯ２）は、ガス雰囲気が変化した時にＣｅの価数を変化することで酸素を吸放出するが、＋４から＋３に変化する際に体積膨張するため、酸素が放出され難い。しかしながら、よりイオン半径の小さいＺｒを添加することで酸素が放出され易くなる。従って、パイロクロア相が相変化して生じた蛍石型相にジルコニウムをドープすると、ジルコニアリッチ蛍石型ＣＺとすることができ、酸素貯蔵能の低下を抑制することができる。 However, even in the case of ceria-zirconia composite oxide having a fluorite structure, the oxygen absorption / release rate changes due to the change in composition, and the oxygen absorption / release rate is high when the zirconia content is higher than the ceria content. It has been known. Ceria (CeO 2 ) absorbs and releases oxygen by changing the valence of Ce when the gas atmosphere changes. However, since it expands in volume when it changes from +4 to +3, oxygen is hardly released. However, oxygen is easily released by adding Zr having a smaller ion radius. Therefore, when zirconium is doped in the fluorite phase generated by the phase change of the pyrochlore phase, a zirconia-rich fluorite-type CZ can be obtained, and a decrease in oxygen storage capacity can be suppressed.
　上述したような構造を有する本発明の複合酸化物材料は、従来公知の方法により調製したパイロクロアＣＺ粒子に熱をかけるなどして表面再配置をあえて生じさせ、その表面に生じた蛍石型相にジルコニアをドープすることにより得ることができる。具体的な調製法としては、例えばパイロクロアＣＺ粒子とジルコニウム塩（オキシ硝酸ジルコニウムなど）とを溶解させた水溶液を蒸発乾固させるか、あるいはパイロクロアＣＺ粒子を懸濁させた水溶液にジルコニウム塩を溶解させた水溶液を加えアンモニア水溶液などで中和して得られた粉末を、大気下で焼成する方法が挙げられる。この調製法では、焼成の過程においてパイロクロアＣＺ粒子の表面再配置とジルコニアのドープが同時に生じていると考えられる。このような調製法によれば、パイロクロアＣＺ粒子と、その表面に形成されたジルコニアリッチ蛍石型ＣＺとが一体化され、すなわち融合して安定化されており、明らかな界面を有さず、容易には分離されないような構造とすることができる。ジルコニウムのドープ量は、パイロクロアＣＺ粒子の重量に対してジルコニア換算で１～２０重量％となる量とすることが好ましい。また、このようにしてパイロクロアＣＺ粒子の表面に形成されたジルコニアリッチ蛍石型ＣＺにおいて、セリウムとジルコニウムの含有量の比は、重量比で５３．５：４６．５～４５：５５の範囲であることが好ましい。 The composite oxide material of the present invention having the structure as described above has a surface rearrangement caused by applying heat to the pyrochlore CZ particles prepared by a conventionally known method, and the fluorite phase generated on the surface. It can be obtained by doping zirconia into the zirconia. As a specific preparation method, for example, an aqueous solution in which pyrochlore CZ particles and zirconium salt (zirconium oxynitrate, etc.) are dissolved is evaporated to dryness, or a zirconium salt is dissolved in an aqueous solution in which pyrochlore CZ particles are suspended. The powder obtained by adding an aqueous solution and neutralizing with an aqueous ammonia solution or the like is calcined in the atmosphere. In this preparation method, it is considered that the surface rearrangement of the pyrochlore CZ particles and the zirconia dope occur simultaneously in the firing process. According to such a preparation method, the pyrochlore CZ particles and the zirconia-rich fluorite-type CZ formed on the surface thereof are integrated, that is, fused and stabilized, and have no obvious interface. A structure that cannot be easily separated can be used. The doping amount of zirconium is preferably 1 to 20% by weight in terms of zirconia with respect to the weight of the pyrochlore CZ particles. In the zirconia-rich fluorite-type CZ formed on the surface of the pyrochlore CZ particles in this way, the ratio of the content of cerium and zirconium is in the range of 53.5: 46.5 to 45:55 by weight. Preferably there is.
　本発明の複合酸化物材料は、パイロクロアＣＺ粒子の表面がジルコニアリッチ蛍石型ＣＺに修飾あるいは被覆したことにより、パイロクロアＣＺ粒子の表面再配置による酸素貯蔵能の低下が抑制されている。さらに、ジルコニアリッチ蛍石型ＣＺ自体も比較的高い酸素貯蔵能を有するため、それをパイロクロアＣＺ粒子の修飾あるいは被覆に利用した本発明の複合酸化物材料では、高い酸素貯蔵能が維持されており、表面が蛍石構造になりやすい修飾あるいは被覆を行っていないパイロクロアＣＺ粒子よりも高い酸素貯蔵能を有する。従って、本発明の複合酸化物材料は、高い酸素貯蔵能を有し、かつ高温下においても酸素貯蔵能が低下しにくい特性を有する。本発明の複合酸化物材料は排ガス浄化触媒用の酸素貯蔵材として特に適している。 In the composite oxide material of the present invention, since the surface of the pyrochlore CZ particles is modified or coated with zirconia-rich fluorite-type CZ, the decrease in oxygen storage capacity due to the surface rearrangement of the pyrochlore CZ particles is suppressed. Furthermore, since the zirconia-rich fluorite-type CZ itself also has a relatively high oxygen storage capacity, the high oxide storage capacity is maintained in the composite oxide material of the present invention that is used for modification or coating of pyrochlore CZ particles. The surface has a higher oxygen storage capacity than pyrochlore CZ particles that are not modified or coated so that the surface tends to have a fluorite structure. Therefore, the composite oxide material of the present invention has a high oxygen storage capacity and has a characteristic that the oxygen storage capacity is not easily lowered even at a high temperature. The composite oxide material of the present invention is particularly suitable as an oxygen storage material for an exhaust gas purification catalyst.
　以下、実施例を用いて本発明をより詳細に説明するが、本発明はこれら実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.
１．サンプル調製
（比較例）
　硝酸セリウム六水和物１２１．８ｇ、オキシ硝酸ジルコニウム二水和物８８．０ｇ、および１８％過酸化水素水３４．６ｇを、イオン交換水５００ｍＬに溶解させた。この溶液と２５％アンモニア水溶液（３００ｇ）とを用いて、逆共沈法により水酸化物沈殿を得た。得られた沈殿を濾過により分離し、乾燥炉にて１５０℃で７時間加熱して水分を除去した後、電気炉にて４００℃で５時間焼成した。得られた粉末を、ボールミルを用いて粉砕し、平均粒径１μｍのセリア－ジルコニア固溶体粉末（１μｍ－ＣＺ粉末）を得た。 1. Sample preparation (comparative example)
121.8 g of cerium nitrate hexahydrate, 88.0 g of zirconium oxynitrate dihydrate, and 34.6 g of 18% hydrogen peroxide solution were dissolved in 500 mL of ion-exchanged water. Using this solution and a 25% aqueous ammonia solution (300 g), a hydroxide precipitate was obtained by the reverse coprecipitation method. The obtained precipitate was separated by filtration, heated in a drying furnace at 150 ° C. for 7 hours to remove moisture, and then baked in an electric furnace at 400 ° C. for 5 hours. The obtained powder was pulverized using a ball mill to obtain a ceria-zirconia solid solution powder (1 μm-CZ powder) having an average particle diameter of 1 μm.
　加圧成型機（ＷＥＴ ＣＩＰ装置）を用い、３０００ｋｇｆ／ｃｍ２の圧力を加えて１μｍ－ＣＺ粉末を成型し、活性炭を入れた黒鉛坩堝内で、Ａｒ雰囲気下、１７００℃で５時間加熱して還元させた。生成物を電気炉にて大気下、５００℃で５時間焼成して酸化させ、パイロクロア型セリア－ジルコニア複合酸化物（パイロクロアＣＺ）を得た。パイロクロアＣＺは、ボールミルを用いて平均２次粒子径１１μｍに粉砕した。 Using a pressure molding machine (WET CIP device), a pressure of 3000 kgf / cm 2 was applied to form a 1 μm-CZ powder, which was then heated in a graphite crucible containing activated carbon at 1700 ° C. for 5 hours in an Ar atmosphere. Reduced. The product was oxidized by calcination at 500 ° C. for 5 hours in the air in an electric furnace to obtain a pyrochlore-type ceria-zirconia composite oxide (pyrochlore CZ). Pyrochlore CZ was pulverized to an average secondary particle size of 11 μm using a ball mill.
（実施例）
　比較例と同じ手順により１１μｍ－パイロクロアＣＺ粉末を調製した。１１μｍ－パイロクロアＣＺ粉末１０．０ｇとオキシ硝酸ジルコニウム二水和物（２．２５ｇ）をイオン交換水５０ｍＬに溶解させ、攪拌しながら蒸発乾固させた。次いで生成物を乾燥炉にて１５０℃で７時間加熱して水分を除去した後、電気炉にて５００℃で２時間焼成した。得られた粉末を、さらに電気炉にて大気下、９００℃で３時間焼成し、本発明のジルコニアリッチ蛍石型ＣＺ修飾パイロクロアＣＺを得た。 (Example)
An 11 μm-pyrochlor CZ powder was prepared by the same procedure as in the comparative example. 11 μm-pyrochlor CZ powder 10.0 g and zirconium oxynitrate dihydrate (2.25 g) were dissolved in 50 mL of ion-exchanged water and evaporated to dryness with stirring. The product was then heated in a drying furnace at 150 ° C. for 7 hours to remove moisture, and then baked in an electric furnace at 500 ° C. for 2 hours. The obtained powder was further baked in an electric furnace at 900 ° C. for 3 hours in the air to obtain a zirconia-rich fluorite-type CZ-modified pyrochlore CZ of the present invention.
２．ＴＥＭ－ＥＤＸ解析
　上記の比較例および実施例で得たサンプルのＴＥＭ－ＥＤＸ解析を行った。図１はＳＴＥＭ－ＥＤＸライン分析の結果を表す図である。それぞれ左側がＴＥＭ像、右側がＴＥＭ像に示されたラインに沿って元素分析を行って得られたスペクトルを示す。比較例のパイロクロアＣＺでは、表面近傍におけるＣｅ／Ｚｒ組成変化は認められない。一方、実施例の本発明のジルコニアリッチ蛍石型ＣＺ修飾パイロクロアＣＺでは、表面付近でＺｒ濃度がＣｅ濃度よりも高くなっており、比較例のパイロクロアＣＺとは明らかな構造が異なることがわかる。 2. TEM-EDX analysis TEM-EDX analysis was performed on the samples obtained in the above comparative examples and examples. FIG. 1 is a diagram showing the results of STEM-EDX line analysis. The left side shows the spectrum obtained by conducting the elemental analysis along the line shown in the TEM image and the right side in the TEM image. In the pyrochlore CZ of the comparative example, the Ce / Zr composition change in the vicinity of the surface is not recognized. On the other hand, in the zirconia-rich fluorite-type CZ-modified pyrochlore CZ of the present invention, the Zr concentration is higher than the Ce concentration near the surface, and it can be seen that the clear structure is different from the pyrochlore CZ of the comparative example.
　図２は、実施例で得たサンプルのＩＦＦＴ解析結果を示す図である。ＴＥＭ像と、ＦＦＴ図形にみられるパイロクロアに特徴的であるスポットの逆フーリエ変換像（ＩＦＦＴ像）を示している。ＩＦＦＴ像から、この実施例のサンプルでは、図２中に示した幅約３０ｎｍの表面近傍領域で長周期構造が崩れ、蛍石構造になっているものと解される。 FIG. 2 is a diagram showing the IFFT analysis results of the samples obtained in the examples. A TEM image and an inverse Fourier transform image (IFFT image) of a spot characteristic of pyrochlore seen in an FFT figure are shown. From the IFFT image, it is understood that in the sample of this example, the long-period structure collapses in the region near the surface having a width of about 30 nm shown in FIG. 2 and has a fluorite structure.
３．高温耐久試験
　上記の比較例および実施例で得たサンプルの高温耐久試験を行った。ただし、サンプルの熱履歴をそろえるために、比較例のサンプルは試験に供する前に予め電気炉にて大気下、９００℃で３時間焼成した。高温耐久試験は、サンプルを電気炉にて、大気雰囲気下１１００℃で５時間加熱処理し、処理後の酸素貯蔵能（ＯＳＣ）を測定することにより行った。 3. High temperature durability test The samples obtained in the above comparative examples and examples were subjected to a high temperature durability test. However, in order to align the thermal history of the sample, the sample of the comparative example was fired at 900 ° C. for 3 hours in the atmosphere in an electric furnace in advance before being subjected to the test. The high temperature endurance test was performed by heating the sample in an electric furnace at 1100 ° C. for 5 hours in an air atmosphere and measuring the oxygen storage capacity (OSC) after the treatment.
　初期または耐久試験後のサンプルを０．２５重量％－Ｐｄ／Ａｌ２Ｏ３粉末と重量比１：１で物理的に混合した。得られた粉末を、加圧成型機（ＷＥＴ ＣＩＰ装置）を用い、１０００ｋｇｆ／ｃｍ２の圧力を加えて成型し、粉砕および篩い分けして１ｍｍ角のペレットを作製した。固定床流通装置に３．０ｇのペレットを配置し、トータル流量１５Ｌの評価用ガスを用いた。評価ガスの温度は４００℃、５００℃または６００℃とした。１％－Ｏ２（Ｎ２バランス）流通時のＣＯ２発生量（２分間）から、ＣＯ＋１／２ Ｏ２→ＣＯ２の反応式に基づき、サンプルから放出されたＯ２量を算出した。セリウムからの酸素の放出は２ＣｅＯ２→Ｃｅ２Ｏ３＋１／２ Ｏ２の反応式で表されることから、仕込みＣｅ量から求められる材料中の格子酸素の理論限界値と、放出されたＯ２量とに基づいて、ＣｅＯ２利用率を求めた。 The sample after the initial or endurance test was physically mixed with 0.25 wt% -Pd / Al 2 O 3 powder at a weight ratio of 1: 1. The obtained powder was molded by applying a pressure of 1000 kgf / cm 2 using a pressure molding machine (WET CIP apparatus), and pulverized and sieved to produce 1 mm square pellets. 3.0 g of pellets were placed in a fixed bed circulation device, and an evaluation gas with a total flow rate of 15 L was used. The temperature of the evaluation gas was 400 ° C., 500 ° C. or 600 ° C. The amount of O 2 released from the sample was calculated from the CO 2 generation amount (2 minutes) during the flow of 1% -O 2 (N 2 balance) based on the reaction equation of CO + 1/2 O 2 → CO 2 . Since the release of oxygen from cerium is represented by the reaction formula 2CeO 2 → Ce 2 O 3 +1/2 O 2 , the theoretical limit value of lattice oxygen in the material determined from the amount of charged Ce and the released O Based on the two quantities, the CeO 2 utilization rate was determined.
　図３に、比較例のパイロクロアＣＺと実施例の表面ジルコニウム修飾パイロクロアＣＺとについて試験を行った結果を示す。例えば５００℃での評価の結果をみると明らかであるように、比較例のパイロクロアＣＺでは耐久試験後にＣｅＯ２利用率が低下しているのに対し、実施例の表面ジルコニア修飾パイロクロアＣＺでは、耐久試験後も比較例のパイロクロアＣＺの初期性能以上のＣｅＯ２利用率を示した。 FIG. 3 shows the results of tests conducted on the pyrochlore CZ of the comparative example and the surface zirconium-modified pyrochlore CZ of the example. For example, as is apparent from the evaluation results at 500 ° C., the utilization rate of CeO 2 in the pyrochlore CZ of the comparative example has decreased after the durability test, whereas the durability of the surface zirconia-modified pyrochlore CZ of the example has decreased. Even after the test, the utilization rate of CeO 2 was higher than the initial performance of the pyrochlore CZ of the comparative example.
　本明細書中で引用した全ての刊行物、特許および特許出願をそのまま参考として本明細書中にとり入れるものとする。 All publications, patents and patent applications cited in this specification shall be incorporated into this specification as they are.

Claims (4)

  1. 　セリア－ジルコニア複合酸化物のパイロクロア構造を有する結晶粒子と、前記粒子表面に存在するセリア－ジルコニア複合酸化物の蛍石構造を有する結晶とを含み、
    　前記セリア－ジルコニア複合酸化物の蛍石構造を有する結晶が、セリアよりもジルコニアを多く含み、かつ前記セリア－ジルコニア複合酸化物のパイロクロア構造を有する結晶粒子と一体化されていることを特徴とする複合酸化物材料。     Crystal grains having a pyrochlore structure of a ceria-zirconia composite oxide, and crystals having a fluorite structure of the ceria-zirconia composite oxide present on the particle surface,
    The crystal having a fluorite structure of the ceria-zirconia composite oxide is characterized in that it contains more zirconia than ceria and is integrated with crystal grains having the pyrochlore structure of the ceria-zirconia composite oxide. Composite oxide material.
  2. 　セリア－ジルコニア複合酸化物のパイロクロア構造を有する結晶粒子に、ジルコニア換算で前記結晶粒子の１～２０重量％のジルコニウムをドープして前記蛍石構造を有する結晶を形成させることにより得られる、請求項１に記載の複合酸化物材料。 The crystal particle having a pyrochlore structure of a ceria-zirconia composite oxide is obtained by doping 1 to 20% by weight of zirconium in terms of zirconia to form a crystal having the fluorite structure. 2. The composite oxide material according to 1.
  3. 　請求項１または２に記載の複合酸化物材料からなる排ガス浄化触媒用酸素貯蔵材。 An oxygen storage material for an exhaust gas purification catalyst comprising the composite oxide material according to claim 1 or 2.
  4. 　請求項１または２に記載の複合酸化物材料を含む排ガス浄化触媒。 An exhaust gas purification catalyst comprising the composite oxide material according to claim 1 or 2.
PCT/JP2013/080770 2012-12-12 2013-11-14 Composite oxide material and exhaust gas purification catalyst using same WO2014091862A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CN201380064838.0A CN104918891A (en) 2012-12-12 2013-11-14 Composite oxide material and exhaust gas purification catalyst using same
US14/439,940 US20150290621A1 (en) 2012-12-12 2013-11-14 Composite oxide material and exhaust gas purifying catalyst using the same
EP13862826.8A EP2933231A4 (en) 2012-12-12 2013-11-14 Composite oxide material and exhaust gas purification catalyst using same
RU2015122223A RU2015122223A (en) 2012-12-12 2013-11-14 COMPLEX OXIDE MATERIAL AND CATALYST FOR EXHAUST GAS CLEANING WITH ITS USE

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2012271387A JP2014114196A (en) 2012-12-12 2012-12-12 Composite oxide material and exhaust gas purification catalyst using the same
JP2012-271387 2012-12-12

Publications (1)

Publication Number Publication Date
WO2014091862A1 true WO2014091862A1 (en) 2014-06-19

Family

ID=50934158

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2013/080770 WO2014091862A1 (en) 2012-12-12 2013-11-14 Composite oxide material and exhaust gas purification catalyst using same

Country Status (6)

Country Link
US (1) US20150290621A1 (en)
EP (1) EP2933231A4 (en)
JP (1) JP2014114196A (en)
CN (1) CN104918891A (en)
RU (1) RU2015122223A (en)
WO (1) WO2014091862A1 (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3378557A4 (en) * 2015-11-17 2019-06-26 Mitsui Mining and Smelting Co., Ltd. Powder for catalysts and catalyst for exhaust gas purification
US10058846B2 (en) 2016-09-05 2018-08-28 Toyota Jidosha Kabushiki Kaisha Catalyst for purifying exhaust gas
JP6855326B2 (en) * 2017-05-26 2021-04-07 株式会社豊田中央研究所 Manufacturing method of oxygen storage material
JP6907890B2 (en) * 2017-11-01 2021-07-21 トヨタ自動車株式会社 Exhaust gas purification catalyst
JP7279697B2 (en) * 2020-09-25 2023-05-23 トヨタ自動車株式会社 Information processing device, information processing method, and information processing program

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004224643A (en) * 2003-01-23 2004-08-12 Sumitomo Metal Mining Co Ltd Cubic tin-tantalum compound oxide and its manufacturing method
JP2011219329A (en) 2010-04-13 2011-11-04 Toyota Central R&D Labs Inc Ceria-zirconia-based compound oxide and method for producing the same, and catalyst for cleaning exhaust gas using the ceria-zirconia-based compound oxide
WO2012105454A1 (en) * 2011-02-01 2012-08-09 株式会社アイシーティー Catalyst for cleaning exhaust gas

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005170774A (en) * 2003-12-15 2005-06-30 Tosoh Corp Compound oxide, method for producing the same, and exhaust gas cleaning catalyst
WO2008093471A1 (en) * 2007-02-01 2008-08-07 Daiichi Kigenso Kagaku Kogyo Co., Ltd. Catalyst system for use in exhaust gas purification apparatus for automobiles, exhaust gas purification apparatus using the catalyst system, and exhaust gas purification method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004224643A (en) * 2003-01-23 2004-08-12 Sumitomo Metal Mining Co Ltd Cubic tin-tantalum compound oxide and its manufacturing method
JP2011219329A (en) 2010-04-13 2011-11-04 Toyota Central R&D Labs Inc Ceria-zirconia-based compound oxide and method for producing the same, and catalyst for cleaning exhaust gas using the ceria-zirconia-based compound oxide
WO2012105454A1 (en) * 2011-02-01 2012-08-09 株式会社アイシーティー Catalyst for cleaning exhaust gas

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP2933231A4

Also Published As

Publication number Publication date
CN104918891A (en) 2015-09-16
US20150290621A1 (en) 2015-10-15
EP2933231A1 (en) 2015-10-21
JP2014114196A (en) 2014-06-26
RU2015122223A (en) 2017-01-17
EP2933231A4 (en) 2015-12-02

Similar Documents

Publication Publication Date Title
JP5815496B2 (en) Composite oxide material and exhaust gas purification catalyst using the same
CN107106981B (en) Exhaust gas purifying catalyst
US10556223B2 (en) Exhaust gas purifying catalyst
JP6474353B2 (en) Precipitation and calcination compositions based on zirconium oxide and cerium oxide
BR112017028424B1 (en) NITROUS OXIDE REMOVAL CATALYST COMPOSITE, EMISSION TREATMENT SYSTEM, AND, METHOD TO TREAT EXHAUST GASES
Wu et al. Effect of preparation methods on the structure and redox behavior of platinum–ceria–zirconia catalysts
WO2017179679A1 (en) Exhaust gas cleaning catalyst, exhaust gas cleaning method, and exhaust gas cleaning system
WO2014091862A1 (en) Composite oxide material and exhaust gas purification catalyst using same
US11559788B2 (en) Oxygen storage and release material, catalyst, exhaust gas purification system, and exhaust gas treatment method
WO2009104386A1 (en) Process for production of catalyst supports and catalyst supports
JP5900395B2 (en) Composite oxide particles and exhaust gas purification catalyst using the same
JP2003277059A (en) Ceria-zirconia compound oxide
WO2006134787A1 (en) Exhaust gas purifying catalyst
JP2007289920A (en) Exhaust-gas cleaning catalyst, its regeneration method, exhaust-gas cleaning apparatus and exhaust-gas cleaning method using it
JP2011224428A (en) Porous catalyst, and method of producing the same
WO2007122917A1 (en) Exhaust gas purifying catalyst and method for producing same
JP4979087B2 (en) Composite oxide powder, production method and production apparatus thereof, and exhaust gas purification catalyst
JP2010030823A (en) Compound oxide and catalyst containing the compound oxide for cleaning exhaust gas
JP2017189761A (en) Method for producing catalyst for exhaust purification
EP2155365B1 (en) Oxygen storage/release material and exhaust gas purifying catalyst comprising the same
JP5030573B2 (en) Composite oxide powder and method for producing the same
JP6923289B2 (en) Oxygen absorption / release material
JP2007260564A (en) Exhaust gas-purifying catalyst and method for regenerating the same
JP2020070219A (en) Ceria-zirconia-based composite oxide oxygen absorption and release material, and exhaust gas purification catalyst
JP5769666B2 (en) Exhaust gas purification catalyst

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 13862826

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 14439940

Country of ref document: US

REEP Request for entry into the european phase

Ref document number: 2013862826

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 2013862826

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2015122223

Country of ref document: RU

Kind code of ref document: A